1. Field of the Invention
The present invention relates in general to fire resistant materials. In particular, the present invention relates to a substrate covering having improved fire resistance.
2. Description of the Related Art
In a wide variety of applications it has long been known to take steps to improve fire resistance to aid in halting the spread of fire. For example, it is well known to provide firewalls within ships, aircraft, automobiles and buildings. Additionally, there are other applications where a specific firewall is not provided, yet the mere presence of the wall or panel provides a certain amount of fire resistance which is deemed acceptable. In such situations the structural integrity of the firewall, wall or panel must be maintained to a certain minimal degree to achieve the desired purpose.
One example would be the cargo sections or bays of aircraft. Such cargo bays often include a composite interior shell or liner which protects the various electrical, hydraulic and fuel lines adjacent the fuselage of the aircraft. During loading and unloading of cargo, however, the cargo bay liner is often damaged. This damage can result in lines being exposed, posing the danger of possible damage to these lines.
Due to the extremely important nature of these lines, repairs of the liner must meet stringent requirements. In particular, a repair patch is required to be fire-resistant, yet structurally sound.
A further example would be an electrical box within a vehicle or structure. Such boxes are typically formed of metal having a hinged door. While the metal of such boxes provides an inherent fire resistance, the seal about the edge of the door can allow ingress of flames, causing damage to the electrical equipment within the box. Similarly, seams between adjacent structural panels may provide an avenue for flame advance, reducing the effectiveness of the panels or wall segments as fire barriers.
One typical fire resistant composition is the class of intumescence materials. Such materials will produce a carbonaceous char in the form of a swelling of the material upon reaching a critical temperature. This char forms an effective barrier against ingress of flames, and also provides a thermal insulator to reduce heat transfer. While it has been known to include intumescence materials within conventional paints and coatings, the intumescence materials are in the form of dispersed ingredients within the paint, resulting in the active intumescence ingredients being relatively far apart in molecular terms. As such, there is some amount of "transport time" and the need for internal turbulence to effectively mix these active ingredients to allow the intumescence reaction to take place. This results in delays and prevents immediate protection of the substrate.
Integrated polymer compositions, wherein all of the elements needed for intumescence are provided within the polymer chain, have more recently been developed in the art. These compositions have preliminarily proven more effective as an intumescence coating since the elements necessary for the intumescence reaction are closely held within the polymer chain, requiring little, if any, transport time before the intumescence reaction is initiated.